content: /**
   * Copyright (c) 2016-present, RxJava Contributors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
   * compliance with the License. You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software distributed under the License is
   * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
   * the License for the specific language governing permissions and limitations under the License.
   */
  
  package io.reactivex.observable.internal.operators;
  
  import static org.junit.Assert.*;
  import static org.mockito.ArgumentMatchers.*;
  import static org.mockito.Mockito.*;
  
  import java.util.*;
  import java.util.concurrent.*;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import org.junit.*;
  import org.mockito.InOrder;
  
  import io.reactivex.common.*;
  import io.reactivex.common.exceptions.TestException;
  import io.reactivex.common.functions.*;
  import io.reactivex.common.internal.functions.Functions;
  import io.reactivex.observable.*;
  import io.reactivex.observable.Observable;
  import io.reactivex.observable.Observer;
  import io.reactivex.observable.observers.*;
  import io.reactivex.observable.subjects.PublishSubject;
  
  public class ObservableZipTest {
      BiFunction<String, String, String> concat2Strings;
      PublishSubject<String> s1;
      PublishSubject<String> s2;
      Observable<String> zipped;
  
      Observer<String> observer;
      InOrder inOrder;
  
      @Before
      public void setUp() {
          concat2Strings = new BiFunction<String, String, String>() {
              @Override
              public String apply(String t1, String t2) {
                  return t1 + "-" + t2;
              }
          };
  
          s1 = PublishSubject.create();
          s2 = PublishSubject.create();
          zipped = Observable.zip(s1, s2, concat2Strings);
  
          observer = TestHelper.mockObserver();
          inOrder = inOrder(observer);
  
          zipped.subscribe(observer);
      }
  
      @SuppressWarnings("unchecked")
      @Test
      public void testCollectionSizeDifferentThanFunction() {
          Function<Object[], String> zipr = Functions.toFunction(getConcatStringIntegerIntArrayZipr());
          //Function3<String, Integer, int[], String>
  
          /* define an Observer to receive aggregated events */
          Observer<String> observer = TestHelper.mockObserver();
  
          @SuppressWarnings("rawtypes")
          Collection ws = java.util.Collections.singleton(Observable.just("one", "two"));
          Observable<String> w = Observable.zip(ws, zipr);
          w.subscribe(observer);
  
          verify(observer, times(1)).onError(any(Throwable.class));
          verify(observer, never()).onComplete();
          verify(observer, never()).onNext(any(String.class));
      }
  
      @Test
      public void testStartpingDifferentLengthObservableSequences1() {
          Observer<String> w = TestHelper.mockObserver();
  
          TestObservable w1 = new TestObservable();
          TestObservable w2 = new TestObservable();
          TestObservable w3 = new TestObservable();
  
          Observable<String> zipW = Observable.zip(
                  Observable.unsafeCreate(w1), Observable.unsafeCreate(w2),
                  Observable.unsafeCreate(w3), getConcat3StringsZipr());
          zipW.subscribe(w);
  
          /* simulate sending data */
          // once for w1
          w1.observer.onNext("1a");
          w1.observer.onComplete();
          // twice for w2
          w2.observer.onNext("2a");
          w2.observer.onNext("2b");
          w2.observer.onComplete();
          // 4 times for w3
          w3.observer.onNext("3a");
          w3.observer.onNext("3b");
          w3.observer.onNext("3c");
          w3.observer.onNext("3d");
          w3.observer.onComplete();
  
          /* we should have been called 1 time on the Observer */
          InOrder io = inOrder(w);
          io.verify(w).onNext("1a2a3a");
  
          io.verify(w, times(1)).onComplete();
      }
  
      @Test
      public void testStartpingDifferentLengthObservableSequences2() {
          Observer<String> w = TestHelper.mockObserver();
  
          TestObservable w1 = new TestObservable();
          TestObservable w2 = new TestObservable();
          TestObservable w3 = new TestObservable();
  
          Observable<String> zipW = Observable.zip(Observable.unsafeCreate(w1), Observable.unsafeCreate(w2), Observable.unsafeCreate(w3), getConcat3StringsZipr());
          zipW.subscribe(w);
  
          /* simulate sending data */
          // 4 times for w1
          w1.observer.onNext("1a");
          w1.observer.onNext("1b");
          w1.observer.onNext("1c");
          w1.observer.onNext("1d");
          w1.observer.onComplete();
          // twice for w2
          w2.observer.onNext("2a");
          w2.observer.onNext("2b");
          w2.observer.onComplete();
          // 1 times for w3
          w3.observer.onNext("3a");
          w3.observer.onComplete();
  
          /* we should have been called 1 time on the Observer */
          InOrder io = inOrder(w);
          io.verify(w).onNext("1a2a3a");
  
          io.verify(w, times(1)).onComplete();
  
      }
  
      BiFunction<Object, Object, String> zipr2 = new BiFunction<Object, Object, String>() {
  
          @Override
          public String apply(Object t1, Object t2) {
              return "" + t1 + t2;
          }
  
      };
      Function3<Object, Object, Object, String> zipr3 = new Function3<Object, Object, Object, String>() {
  
          @Override
          public String apply(Object t1, Object t2, Object t3) {
              return "" + t1 + t2 + t3;
          }
  
      };
  
      /**
       * Testing internal private logic due to the complexity so I want to use TDD to test as a I build it rather than relying purely on the overall functionality expected by the public methods.
       */
      @Test
      public void testAggregatorSimple() {
          PublishSubject<String> r1 = PublishSubject.create();
          PublishSubject<String> r2 = PublishSubject.create();
          /* define an Observer to receive aggregated events */
          Observer<String> observer = TestHelper.mockObserver();
  
          Observable.zip(r1, r2, zipr2).subscribe(observer);
  
          /* simulate the Observables pushing data into the aggregator */
          r1.onNext("hello");
          r2.onNext("world");
  
          InOrder inOrder = inOrder(observer);
  
          verify(observer, never()).onError(any(Throwable.class));
          verify(observer, never()).onComplete();
          inOrder.verify(observer, times(1)).onNext("helloworld");
  
          r1.onNext("hello ");
          r2.onNext("again");
  
          verify(observer, never()).onError(any(Throwable.class));
          verify(observer, never()).onComplete();
          inOrder.verify(observer, times(1)).onNext("hello again");
  
          r1.onComplete();
          r2.onComplete();
  
          inOrder.verify(observer, never()).onNext(anyString());
          verify(observer, times(1)).onComplete();
      }
  
      @Test
      public void testAggregatorDifferentSizedResultsWithOnComplete() {
          /* create the aggregator which will execute the zip function when all Observables provide values */
          /* define an Observer to receive aggregated events */
          PublishSubject<String> r1 = PublishSubject.create();
          PublishSubject<String> r2 = PublishSubject.create();
          /* define an Observer to receive aggregated events */
          Observer<String> observer = TestHelper.mockObserver();
          Observable.zip(r1, r2, zipr2).subscribe(observer);
  
          /* simulate the Observables pushing data into the aggregator */
          r1.onNext("hello");
          r2.onNext("world");
          r2.onComplete();
  
          InOrder inOrder = inOrder(observer);
  
          inOrder.verify(observer, never()).onError(any(Throwable.class));
          inOrder.verify(observer, times(1)).onNext("helloworld");
          inOrder.verify(observer, times(1)).onComplete();
  
          r1.onNext("hi");
          r1.onComplete();
  
          inOrder.verify(observer, never()).onError(any(Throwable.class));
          inOrder.verify(observer, never()).onComplete();
          inOrder.verify(observer, never()).onNext(anyString());
      }
  
      @Test
      public void testAggregateMultipleTypes() {
          PublishSubject<String> r1 = PublishSubject.create();
          PublishSubject<Integer> r2 = PublishSubject.create();
          /* define an Observer to receive aggregated events */
          Observer<String> observer = TestHelper.mockObserver();
  
          Observable.zip(r1, r2, zipr2).subscribe(observer);
  
          /* simulate the Observables pushing data into the aggregator */
          r1.onNext("hello");
          r2.onNext(1);
          r2.onComplete();
  
          InOrder inOrder = inOrder(observer);
  
          inOrder.verify(observer, never()).onError(any(Throwable.class));
          inOrder.verify(observer, times(1)).onNext("hello1");
          inOrder.verify(observer, times(1)).onComplete();
  
          r1.onNext("hi");
          r1.onComplete();
  
          inOrder.verify(observer, never()).onError(any(Throwable.class));
          inOrder.verify(observer, never()).onComplete();
          inOrder.verify(observer, never()).onNext(anyString());
      }
  
      @Test
      public void testAggregate3Types() {
          PublishSubject<String> r1 = PublishSubject.create();
          PublishSubject<Integer> r2 = PublishSubject.create();
          PublishSubject<List<Integer>> r3 = PublishSubject.create();
          /* define an Observer to receive aggregated events */
          Observer<String> observer = TestHelper.mockObserver();
  
          Observable.zip(r1, r2, r3, zipr3).subscribe(observer);
  
          /* simulate the Observables pushing data into the aggregator */
          r1.onNext("hello");
          r2.onNext(2);
          r3.onNext(Arrays.asList(5, 6, 7));
  
          verify(observer, never()).onError(any(Throwable.class));
          verify(observer, never()).onComplete();
          verify(observer, times(1)).onNext("hello2[5, 6, 7]");
      }
  
      @Test
      public void testAggregatorsWithDifferentSizesAndTiming() {
          PublishSubject<String> r1 = PublishSubject.create();
          PublishSubject<String> r2 = PublishSubject.create();
          /* define an Observer to receive aggregated events */
          Observer<String> observer = TestHelper.mockObserver();
  
          Observable.zip(r1, r2, zipr2).subscribe(observer);
  
          /* simulate the Observables pushing data into the aggregator */
          r1.onNext("one");
          r1.onNext("two");
          r1.onNext("three");
          r2.onNext("A");
  
          verify(observer, never()).onError(any(Throwable.class));
          verify(observer, never()).onComplete();
          verify(observer, times(1)).onNext("oneA");
  
          r1.onNext("four");
          r1.onComplete();
          r2.onNext("B");
          verify(observer, times(1)).onNext("twoB");
          r2.onNext("C");
          verify(observer, times(1)).onNext("threeC");
          r2.onNext("D");
          verify(observer, times(1)).onNext("fourD");
          r2.onNext("E");
          verify(observer, never()).onNext("E");
          r2.onComplete();
  
          verify(observer, never()).onError(any(Throwable.class));
          verify(observer, times(1)).onComplete();
      }
  
      @Test
      public void testAggregatorError() {
          PublishSubject<String> r1 = PublishSubject.create();
          PublishSubject<String> r2 = PublishSubject.create();
          /* define an Observer to receive aggregated events */
          Observer<String> observer = TestHelper.mockObserver();
  
          Observable.zip(r1, r2, zipr2).subscribe(observer);
  
          /* simulate the Observables pushing data into the aggregator */
          r1.onNext("hello");
          r2.onNext("world");
  
          verify(observer, never()).onError(any(Throwable.class));
          verify(observer, never()).onComplete();
          verify(observer, times(1)).onNext("helloworld");
  
          r1.onError(new RuntimeException(""));
          r1.onNext("hello");
          r2.onNext("again");
  
          verify(observer, times(1)).onError(any(Throwable.class));
          verify(observer, never()).onComplete();
          // we don't want to be called again after an error
          verify(observer, times(0)).onNext("helloagain");
      }
  
      @Test
      public void testAggregatorUnsubscribe() {
          PublishSubject<String> r1 = PublishSubject.create();
          PublishSubject<String> r2 = PublishSubject.create();
          /* define an Observer to receive aggregated events */
          Observer<String> observer = TestHelper.mockObserver();
          TestObserver<String> ts = new TestObserver<String>(observer);
  
          Observable.zip(r1, r2, zipr2).subscribe(ts);
  
          /* simulate the Observables pushing data into the aggregator */
          r1.onNext("hello");
          r2.onNext("world");
  
          verify(observer, never()).onError(any(Throwable.class));
          verify(observer, never()).onComplete();
          verify(observer, times(1)).onNext("helloworld");
  
          ts.dispose();
          r1.onNext("hello");
          r2.onNext("again");
  
          verify(observer, times(0)).onError(any(Throwable.class));
          verify(observer, never()).onComplete();
          // we don't want to be called again after an error
          verify(observer, times(0)).onNext("helloagain");
      }
  
      @Test
      public void testAggregatorEarlyCompletion() {
          PublishSubject<String> r1 = PublishSubject.create();
          PublishSubject<String> r2 = PublishSubject.create();
          /* define an Observer to receive aggregated events */
          Observer<String> observer = TestHelper.mockObserver();
  
          Observable.zip(r1, r2, zipr2).subscribe(observer);
  
          /* simulate the Observables pushing data into the aggregator */
          r1.onNext("one");
          r1.onNext("two");
          r1.onComplete();
          r2.onNext("A");
  
          InOrder inOrder = inOrder(observer);
  
          inOrder.verify(observer, never()).onError(any(Throwable.class));
          inOrder.verify(observer, never()).onComplete();
          inOrder.verify(observer, times(1)).onNext("oneA");
  
          r2.onComplete();
  
          inOrder.verify(observer, never()).onError(any(Throwable.class));
          inOrder.verify(observer, times(1)).onComplete();
          inOrder.verify(observer, never()).onNext(anyString());
      }
  
      @Test
      public void testStart2Types() {
          BiFunction<String, Integer, String> zipr = getConcatStringIntegerZipr();
  
          /* define an Observer to receive aggregated events */
          Observer<String> observer = TestHelper.mockObserver();
  
          Observable<String> w = Observable.zip(Observable.just("one", "two"), Observable.just(2, 3, 4), zipr);
          w.subscribe(observer);
  
          verify(observer, never()).onError(any(Throwable.class));
          verify(observer, times(1)).onComplete();
          verify(observer, times(1)).onNext("one2");
          verify(observer, times(1)).onNext("two3");
          verify(observer, never()).onNext("4");
      }
  
      @Test
      public void testStart3Types() {
          Function3<String, Integer, int[], String> zipr = getConcatStringIntegerIntArrayZipr();
  
          /* define an Observer to receive aggregated events */
          Observer<String> observer = TestHelper.mockObserver();
  
          Observable<String> w = Observable.zip(Observable.just("one", "two"), Observable.just(2), Observable.just(new int[] { 4, 5, 6 }), zipr);
          w.subscribe(observer);
  
          verify(observer, never()).onError(any(Throwable.class));
          verify(observer, times(1)).onComplete();
          verify(observer, times(1)).onNext("one2[4, 5, 6]");
          verify(observer, never()).onNext("two");
      }
  
      @Test
      public void testOnNextExceptionInvokesOnError() {
          BiFunction<Integer, Integer, Integer> zipr = getDivideZipr();
  
          Observer<Integer> observer = TestHelper.mockObserver();
  
          Observable<Integer> w = Observable.zip(Observable.just(10, 20, 30), Observable.just(0, 1, 2), zipr);
          w.subscribe(observer);
  
          verify(observer, times(1)).onError(any(Throwable.class));
      }
  
      @Test
      public void testOnFirstCompletion() {
          PublishSubject<String> oA = PublishSubject.create();
          PublishSubject<String> oB = PublishSubject.create();
  
          Observer<String> obs = TestHelper.mockObserver();
  
          Observable<String> o = Observable.zip(oA, oB, getConcat2Strings());
          o.subscribe(obs);
  
          InOrder io = inOrder(obs);
  
          oA.onNext("a1");
          io.verify(obs, never()).onNext(anyString());
          oB.onNext("b1");
          io.verify(obs, times(1)).onNext("a1-b1");
          oB.onNext("b2");
          io.verify(obs, never()).onNext(anyString());
          oA.onNext("a2");
          io.verify(obs, times(1)).onNext("a2-b2");
  
          oA.onNext("a3");
          oA.onNext("a4");
          oA.onNext("a5");
          oA.onComplete();
  
          // SHOULD ONCOMPLETE BE EMITTED HERE INSTEAD OF WAITING
          // FOR B3, B4, B5 TO BE EMITTED?
  
          oB.onNext("b3");
          oB.onNext("b4");
          oB.onNext("b5");
  
          io.verify(obs, times(1)).onNext("a3-b3");
          io.verify(obs, times(1)).onNext("a4-b4");
          io.verify(obs, times(1)).onNext("a5-b5");
  
          // WE RECEIVE THE ONCOMPLETE HERE
          io.verify(obs, times(1)).onComplete();
  
          oB.onNext("b6");
          oB.onNext("b7");
          oB.onNext("b8");
          oB.onNext("b9");
          // never completes (infinite stream for example)
  
          // we should receive nothing else despite oB continuing after oA completed
          io.verifyNoMoreInteractions();
      }
  
      @Test
      public void testOnErrorTermination() {
          PublishSubject<String> oA = PublishSubject.create();
          PublishSubject<String> oB = PublishSubject.create();
  
          Observer<String> obs = TestHelper.mockObserver();
  
          Observable<String> o = Observable.zip(oA, oB, getConcat2Strings());
          o.subscribe(obs);
  
          InOrder io = inOrder(obs);
  
          oA.onNext("a1");
          io.verify(obs, never()).onNext(anyString());
          oB.onNext("b1");
          io.verify(obs, times(1)).onNext("a1-b1");
          oB.onNext("b2");
          io.verify(obs, never()).onNext(anyString());
          oA.onNext("a2");
          io.verify(obs, times(1)).onNext("a2-b2");
  
          oA.onNext("a3");
          oA.onNext("a4");
          oA.onNext("a5");
          oA.onError(new RuntimeException("forced failure"));
  
          // it should emit failure immediately
          io.verify(obs, times(1)).onError(any(RuntimeException.class));
  
          oB.onNext("b3");
          oB.onNext("b4");
          oB.onNext("b5");
          oB.onNext("b6");
          oB.onNext("b7");
          oB.onNext("b8");
          oB.onNext("b9");
          // never completes (infinite stream for example)
  
          // we should receive nothing else despite oB continuing after oA completed
          io.verifyNoMoreInteractions();
      }
  
      private BiFunction<String, String, String> getConcat2Strings() {
          return new BiFunction<String, String, String>() {
  
              @Override
              public String apply(String t1, String t2) {
                  return t1 + "-" + t2;
              }
          };
      }
  
      private BiFunction<Integer, Integer, Integer> getDivideZipr() {
          BiFunction<Integer, Integer, Integer> zipr = new BiFunction<Integer, Integer, Integer>() {
  
              @Override
              public Integer apply(Integer i1, Integer i2) {
                  return i1 / i2;
              }
  
          };
          return zipr;
      }
  
      private Function3<String, String, String, String> getConcat3StringsZipr() {
          Function3<String, String, String, String> zipr = new Function3<String, String, String, String>() {
  
              @Override
              public String apply(String a1, String a2, String a3) {
                  if (a1 == null) {
                      a1 = "";
                  }
                  if (a2 == null) {
                      a2 = "";
                  }
                  if (a3 == null) {
                      a3 = "";
                  }
                  return a1 + a2 + a3;
              }
  
          };
          return zipr;
      }
  
      private BiFunction<String, Integer, String> getConcatStringIntegerZipr() {
          BiFunction<String, Integer, String> zipr = new BiFunction<String, Integer, String>() {
  
              @Override
              public String apply(String s, Integer i) {
                  return getStringValue(s) + getStringValue(i);
              }
  
          };
          return zipr;
      }
  
      private Function3<String, Integer, int[], String> getConcatStringIntegerIntArrayZipr() {
          Function3<String, Integer, int[], String> zipr = new Function3<String, Integer, int[], String>() {
  
              @Override
              public String apply(String s, Integer i, int[] iArray) {
                  return getStringValue(s) + getStringValue(i) + getStringValue(iArray);
              }
  
          };
          return zipr;
      }
  
      private static String getStringValue(Object o) {
          if (o == null) {
              return "";
          } else {
              if (o instanceof int[]) {
                  return Arrays.toString((int[]) o);
              } else {
                  return String.valueOf(o);
              }
          }
      }
  
      private static class TestObservable implements ObservableSource<String> {
  
          Observer<? super String> observer;
  
          @Override
          public void subscribe(Observer<? super String> observer) {
              // just store the variable where it can be accessed so we can manually trigger it
              this.observer = observer;
              observer.onSubscribe(Disposables.empty());
          }
  
      }
  
      @Test
      public void testFirstCompletesThenSecondInfinite() {
          s1.onNext("a");
          s1.onNext("b");
          s1.onComplete();
          s2.onNext("1");
          inOrder.verify(observer, times(1)).onNext("a-1");
          s2.onNext("2");
          inOrder.verify(observer, times(1)).onNext("b-2");
          inOrder.verify(observer, times(1)).onComplete();
          inOrder.verifyNoMoreInteractions();
      }
  
      @Test
      public void testSecondInfiniteThenFirstCompletes() {
          s2.onNext("1");
          s2.onNext("2");
          s1.onNext("a");
          inOrder.verify(observer, times(1)).onNext("a-1");
          s1.onNext("b");
          inOrder.verify(observer, times(1)).onNext("b-2");
          s1.onComplete();
          inOrder.verify(observer, times(1)).onComplete();
          inOrder.verifyNoMoreInteractions();
      }
  
      @Test
      public void testSecondCompletesThenFirstInfinite() {
          s2.onNext("1");
          s2.onNext("2");
          s2.onComplete();
          s1.onNext("a");
          inOrder.verify(observer, times(1)).onNext("a-1");
          s1.onNext("b");
          inOrder.verify(observer, times(1)).onNext("b-2");
          inOrder.verify(observer, times(1)).onComplete();
          inOrder.verifyNoMoreInteractions();
      }
  
      @Test
      public void testFirstInfiniteThenSecondCompletes() {
          s1.onNext("a");
          s1.onNext("b");
          s2.onNext("1");
          inOrder.verify(observer, times(1)).onNext("a-1");
          s2.onNext("2");
          inOrder.verify(observer, times(1)).onNext("b-2");
          s2.onComplete();
          inOrder.verify(observer, times(1)).onComplete();
          inOrder.verifyNoMoreInteractions();
      }
  
      @Test
      public void testFirstFails() {
          s2.onNext("a");
          s1.onError(new RuntimeException("Forced failure"));
  
          inOrder.verify(observer, times(1)).onError(any(RuntimeException.class));
  
          s2.onNext("b");
          s1.onNext("1");
          s1.onNext("2");
  
          inOrder.verify(observer, never()).onComplete();
          inOrder.verify(observer, never()).onNext(any(String.class));
          inOrder.verifyNoMoreInteractions();
      }
  
      @Test
      public void testSecondFails() {
          s1.onNext("a");
          s1.onNext("b");
          s2.onError(new RuntimeException("Forced failure"));
  
          inOrder.verify(observer, times(1)).onError(any(RuntimeException.class));
  
          s2.onNext("1");
          s2.onNext("2");
  
          inOrder.verify(observer, never()).onComplete();
          inOrder.verify(observer, never()).onNext(any(String.class));
          inOrder.verifyNoMoreInteractions();
      }
  
      @Test
      public void testStartWithOnCompletedTwice() {
          // issue: https://groups.google.com/forum/#!topic/rxjava/79cWTv3TFp0
          // The problem is the original "zip" implementation does not wrap
          // an internal observer with a SafeSubscriber. However, in the "zip",
          // it may calls "onComplete" twice. That breaks the Rx contract.
  
          // This test tries to emulate this case.
          // As "TestHelper.mockObserver()" will create an instance in the package "rx",
          // we need to wrap "TestHelper.mockObserver()" with an observer instance
          // which is in the package "rx.operators".
          final Observer<Integer> observer = TestHelper.mockObserver();
  
          Observable.zip(Observable.just(1),
                  Observable.just(1), new BiFunction<Integer, Integer, Integer>() {
                      @Override
                      public Integer apply(Integer a, Integer b) {
                          return a + b;
                      }
                  }).subscribe(new DefaultObserver<Integer>() {
  
              @Override
              public void onComplete() {
                  observer.onComplete();
              }
  
              @Override
              public void onError(Throwable e) {
                  observer.onError(e);
              }
  
              @Override
              public void onNext(Integer args) {
                  observer.onNext(args);
              }
  
          });
  
          InOrder inOrder = inOrder(observer);
          inOrder.verify(observer, times(1)).onNext(2);
          inOrder.verify(observer, times(1)).onComplete();
          inOrder.verifyNoMoreInteractions();
      }
  
      @Test
      public void testStart() {
          Observable<String> os = OBSERVABLE_OF_5_INTEGERS
                  .zipWith(OBSERVABLE_OF_5_INTEGERS, new BiFunction<Integer, Integer, String>() {
  
                      @Override
                      public String apply(Integer a, Integer b) {
                          return a + "-" + b;
                      }
                  });
  
          final ArrayList<String> list = new ArrayList<String>();
          os.subscribe(new Consumer<String>() {
  
              @Override
              public void accept(String s) {
                  System.out.println(s);
                  list.add(s);
              }
          });
  
          assertEquals(5, list.size());
          assertEquals("1-1", list.get(0));
          assertEquals("2-2", list.get(1));
          assertEquals("5-5", list.get(4));
      }
  
      @Test
      public void testStartAsync() throws InterruptedException {
          Observable<String> os = ASYNC_OBSERVABLE_OF_INFINITE_INTEGERS(new CountDownLatch(1))
                  .zipWith(ASYNC_OBSERVABLE_OF_INFINITE_INTEGERS(new CountDownLatch(1)), new BiFunction<Integer, Integer, String>() {
  
                      @Override
                      public String apply(Integer a, Integer b) {
                          return a + "-" + b;
                      }
                  }).take(5);
  
          TestObserver<String> ts = new TestObserver<String>();
          os.subscribe(ts);
  
          ts.awaitTerminalEvent();
          ts.assertNoErrors();
  
          assertEquals(5, ts.valueCount());
          assertEquals("1-1", ts.values().get(0));
          assertEquals("2-2", ts.values().get(1));
          assertEquals("5-5", ts.values().get(4));
      }
  
      @Test
      public void testStartInfiniteAndFinite() throws InterruptedException {
          final CountDownLatch latch = new CountDownLatch(1);
          final CountDownLatch infiniteObservable = new CountDownLatch(1);
          Observable<String> os = OBSERVABLE_OF_5_INTEGERS
                  .zipWith(ASYNC_OBSERVABLE_OF_INFINITE_INTEGERS(infiniteObservable), new BiFunction<Integer, Integer, String>() {
  
                      @Override
                      public String apply(Integer a, Integer b) {
                          return a + "-" + b;
                      }
                  });
  
          final ArrayList<String> list = new ArrayList<String>();
          os.subscribe(new DefaultObserver<String>() {
  
              @Override
              public void onComplete() {
                  latch.countDown();
              }
  
              @Override
              public void onError(Throwable e) {
                  e.printStackTrace();
                  latch.countDown();
              }
  
              @Override
              public void onNext(String s) {
                  System.out.println(s);
                  list.add(s);
              }
          });
  
          latch.await(1000, TimeUnit.MILLISECONDS);
          if (!infiniteObservable.await(2000, TimeUnit.MILLISECONDS)) {
              throw new RuntimeException("didn't unsubscribe");
          }
  
          assertEquals(5, list.size());
          assertEquals("1-1", list.get(0));
          assertEquals("2-2", list.get(1));
          assertEquals("5-5", list.get(4));
      }
  
      @Test
      @Ignore("Null values not allowed")
      public void testEmitNull() {
          Observable<Integer> oi = Observable.just(1, null, 3);
          Observable<String> os = Observable.just("a", "b", null);
          Observable<String> o = Observable.zip(oi, os, new BiFunction<Integer, String, String>() {
  
              @Override
              public String apply(Integer t1, String t2) {
                  return t1 + "-" + t2;
              }
  
          });
  
          final ArrayList<String> list = new ArrayList<String>();
          o.subscribe(new Consumer<String>() {
  
              @Override
              public void accept(String s) {
                  System.out.println(s);
                  list.add(s);
              }
          });
  
          assertEquals(3, list.size());
          assertEquals("1-a", list.get(0));
          assertEquals("null-b", list.get(1));
          assertEquals("3-null", list.get(2));
      }
  
      @SuppressWarnings("rawtypes")
      static String kind(Notification notification) {
          if (notification.isOnError()) {
              return "OnError";
          }
          if (notification.isOnNext()) {
              return "OnNext";
          }
          return "OnComplete";
      }
  
      @SuppressWarnings("rawtypes")
      static String value(Notification notification) {
          if (notification.isOnNext()) {
              return String.valueOf(notification.getValue());
          }
          return "null";
      }
  
      @Test
      public void testEmitMaterializedNotifications() {
          Observable<Notification<Integer>> oi = Observable.just(1, 2, 3).materialize();
          Observable<Notification<String>> os = Observable.just("a", "b", "c").materialize();
          Observable<String> o = Observable.zip(oi, os, new BiFunction<Notification<Integer>, Notification<String>, String>() {
  
              @Override
              public String apply(Notification<Integer> t1, Notification<String> t2) {
                  return kind(t1) + "_" + value(t1) + "-" + kind(t2) + "_" + value(t2);
              }
  
          });
  
          final ArrayList<String> list = new ArrayList<String>();
          o.subscribe(new Consumer<String>() {
  
              @Override
              public void accept(String s) {
                  System.out.println(s);
                  list.add(s);
              }
          });
  
          assertEquals(4, list.size());
          assertEquals("OnNext_1-OnNext_a", list.get(0));
          assertEquals("OnNext_2-OnNext_b", list.get(1));
          assertEquals("OnNext_3-OnNext_c", list.get(2));
          assertEquals("OnComplete_null-OnComplete_null", list.get(3));
      }
  
      @Test
      public void testStartEmptyObservables() {
  
          Observable<String> o = Observable.zip(Observable.<Integer> empty(), Observable.<String> empty(), new BiFunction<Integer, String, String>() {
  
              @Override
              public String apply(Integer t1, String t2) {
                  return t1 + "-" + t2;
              }
  
          });
  
          final ArrayList<String> list = new ArrayList<String>();
          o.subscribe(new Consumer<String>() {
  
              @Override
              public void accept(String s) {
                  System.out.println(s);
                  list.add(s);
              }
          });
  
          assertEquals(0, list.size());
      }
  
      @Test
      public void testStartEmptyList() {
  
          final Object invoked = new Object();
          Collection<Observable<Object>> observables = Collections.emptyList();
  
          Observable<Object> o = Observable.zip(observables, new Function<Object[], Object>() {
              @Override
              public Object apply(final Object[] args) {
                  assertEquals("No argument should have been passed", 0, args.length);
                  return invoked;
              }
          });
  
          TestObserver<Object> ts = new TestObserver<Object>();
          o.subscribe(ts);
          ts.awaitTerminalEvent(200, TimeUnit.MILLISECONDS);
          ts.assertNoValues();
      }
  
      /**
       * Expect NoSuchElementException instead of blocking forever as zip should emit onComplete and no onNext
       * and last() expects at least a single response.
       */
      @Test(expected = NoSuchElementException.class)
      public void testStartEmptyListBlocking() {
  
          final Object invoked = new Object();
          Collection<Observable<Object>> observables = Collections.emptyList();
  
          Observable<Object> o = Observable.zip(observables, new Function<Object[], Object>() {
              @Override
              public Object apply(final Object[] args) {
                  assertEquals("No argument should have been passed", 0, args.length);
                  return invoked;
              }
          });
  
          o.blockingLast();
      }
  
      @Test
      public void testDownstreamBackpressureRequestsWithFiniteSyncObservables() {
          AtomicInteger generatedA = new AtomicInteger();
          AtomicInteger generatedB = new AtomicInteger();
          Observable<Integer> o1 = createInfiniteObservable(generatedA).take(Observable.bufferSize() * 2);
          Observable<Integer> o2 = createInfiniteObservable(generatedB).take(Observable.bufferSize() * 2);
  
          TestObserver<String> ts = new TestObserver<String>();
          Observable.zip(o1, o2, new BiFunction<Integer, Integer, String>() {
  
              @Override
              public String apply(Integer t1, Integer t2) {
                  return t1 + "-" + t2;
              }
  
          }).observeOn(Schedulers.computation()).take(Observable.bufferSize() * 2).subscribe(ts);
  
          ts.awaitTerminalEvent();
          ts.assertNoErrors();
          assertEquals(Observable.bufferSize() * 2, ts.valueCount());
          System.out.println("Generated => A: " + generatedA.get() + " B: " + generatedB.get());
          assertTrue(generatedA.get() < (Observable.bufferSize() * 3));
          assertTrue(generatedB.get() < (Observable.bufferSize() * 3));
      }
  
      private Observable<Integer> createInfiniteObservable(final AtomicInteger generated) {
          Observable<Integer> o = Observable.fromIterable(new Iterable<Integer>() {
              @Override
              public Iterator<Integer> iterator() {
                  return new Iterator<Integer>() {
  
                      @Override
                      public void remove() {
                      }
  
                      @Override
                      public Integer next() {
                          return generated.getAndIncrement();
                      }
  
                      @Override
                      public boolean hasNext() {
                          return true;
                      }
                  };
              }
          });
          return o;
      }
  
      Observable<Integer> OBSERVABLE_OF_5_INTEGERS = OBSERVABLE_OF_5_INTEGERS(new AtomicInteger());
  
      Observable<Integer> OBSERVABLE_OF_5_INTEGERS(final AtomicInteger numEmitted) {
          return Observable.unsafeCreate(new ObservableSource<Integer>() {
  
              @Override
              public void subscribe(final Observer<? super Integer> o) {
                  Disposable d = Disposables.empty();
                  o.onSubscribe(d);
                  for (int i = 1; i <= 5; i++) {
                      if (d.isDisposed()) {
                          break;
                      }
                      numEmitted.incrementAndGet();
                      o.onNext(i);
                      Thread.yield();
                  }
                  o.onComplete();
              }
  
          });
      }
  
      Observable<Integer> ASYNC_OBSERVABLE_OF_INFINITE_INTEGERS(final CountDownLatch latch) {
          return Observable.unsafeCreate(new ObservableSource<Integer>() {
  
              @Override
              public void subscribe(final Observer<? super Integer> o) {
                  final Disposable d = Disposables.empty();
                  o.onSubscribe(d);
                  Thread t = new Thread(new Runnable() {
  
                      @Override
                      public void run() {
                          System.out.println("-------> subscribe to infinite sequence");
                          System.out.println("Starting thread: " + Thread.currentThread());
                          int i = 1;
                          while (!d.isDisposed()) {
                              o.onNext(i++);
                              Thread.yield();
                          }
                          o.onComplete();
                          latch.countDown();
                          System.out.println("Ending thread: " + Thread.currentThread());
                      }
                  });
                  t.start();
  
              }
  
          });
      }
  
      @Test(timeout = 30000)
      public void testIssue1812() {
          // https://github.com/ReactiveX/RxJava/issues/1812
          Observable<Integer> zip1 = Observable.zip(Observable.range(0, 1026), Observable.range(0, 1026),
                  new BiFunction<Integer, Integer, Integer>() {
  
                      @Override
                      public Integer apply(Integer i1, Integer i2) {
                          return i1 + i2;
                      }
                  });
          Observable<Integer> zip2 = Observable.zip(zip1, Observable.range(0, 1026),
                  new BiFunction<Integer, Integer, Integer>() {
  
                      @Override
                      public Integer apply(Integer i1, Integer i2) {
                          return i1 + i2;
                      }
                  });
          List<Integer> expected = new ArrayList<Integer>();
          for (int i = 0; i < 1026; i++) {
              expected.add(i * 3);
          }
          assertEquals(expected, zip2.toList().blockingGet());
      }
  
      @Test(timeout = 10000)
      public void testZipRace() {
          long startTime = System.currentTimeMillis();
          Observable<Integer> src = Observable.just(1).subscribeOn(Schedulers.computation());
  
          // now try and generate a hang by zipping src with itself repeatedly. A
          // time limit of 9 seconds ( 1 second less than the test timeout) is
          // used so that this test will not timeout on slow machines.
          int i = 0;
          while (System.currentTimeMillis() - startTime < 9000 && i++ < 100000) {
              int value = Observable.zip(src, src, new BiFunction<Integer, Integer, Integer>() {
                  @Override
                  public Integer apply(Integer t1, Integer t2) {
                      return t1 + t2 * 10;
                  }
              }).blockingSingle(0);
  
              Assert.assertEquals(11, value);
          }
      }
  
      @Test
      public void zip2() {
          Observable.zip(Observable.just(1),
                  Observable.just(2),
              new BiFunction<Integer, Integer, Object>() {
                  @Override
                  public Object apply(Integer a, Integer b) throws Exception {
                      return "" + a + b;
                  }
              }
          )
          .test()
          .assertResult("12");
      }
  
      @Test
      public void zip3() {
          Observable.zip(Observable.just(1),
                  Observable.just(2), Observable.just(3),
              new Function3<Integer, Integer, Integer, Object>() {
                  @Override
                  public Object apply(Integer a, Integer b, Integer c) throws Exception {
                      return "" + a + b + c;
                  }
              }
          )
          .test()
          .assertResult("123");
      }
  
      @Test
      public void zip4() {
          Observable.zip(Observable.just(1),
                  Observable.just(2), Observable.just(3),
                  Observable.just(4),
              new Function4<Integer, Integer, Integer, Integer, Object>() {
                  @Override
                  public Object apply(Integer a, Integer b, Integer c, Integer d) throws Exception {
                      return "" + a + b + c + d;
                  }
              }
          )
          .test()
          .assertResult("1234");
      }
  
      @Test
      public void zip5() {
          Observable.zip(Observable.just(1),
                  Observable.just(2), Observable.just(3),
                  Observable.just(4), Observable.just(5),
              new Function5<Integer, Integer, Integer, Integer, Integer, Object>() {
                  @Override
                  public Object apply(Integer a, Integer b, Integer c, Integer d, Integer e) throws Exception {
                      return "" + a + b + c + d + e;
                  }
              }
          )
          .test()
          .assertResult("12345");
      }
  
      @Test
      public void zip6() {
          Observable.zip(Observable.just(1),
                  Observable.just(2), Observable.just(3),
                  Observable.just(4), Observable.just(5),
                  Observable.just(6),
              new Function6<Integer, Integer, Integer, Integer, Integer, Integer, Object>() {
                  @Override
                  public Object apply(Integer a, Integer b, Integer c, Integer d, Integer e, Integer f) throws Exception {
                      return "" + a + b + c + d + e + f;
                  }
              }
          )
          .test()
          .assertResult("123456");
      }
  
      @Test
      public void zip7() {
          Observable.zip(Observable.just(1),
                  Observable.just(2), Observable.just(3),
                  Observable.just(4), Observable.just(5),
                  Observable.just(6), Observable.just(7),
              new Function7<Integer, Integer, Integer, Integer, Integer, Integer, Integer, Object>() {
                  @Override
                  public Object apply(Integer a, Integer b, Integer c, Integer d, Integer e, Integer f, Integer g)
                          throws Exception {
                      return "" + a + b + c + d + e + f + g;
                  }
              }
          )
          .test()
          .assertResult("1234567");
      }
  
      @Test
      public void zip8() {
          Observable.zip(Observable.just(1),
                  Observable.just(2), Observable.just(3),
                  Observable.just(4), Observable.just(5),
                  Observable.just(6), Observable.just(7),
                  Observable.just(8),
              new Function8<Integer, Integer, Integer, Integer, Integer, Integer, Integer, Integer, Object>() {
                  @Override
                  public Object apply(Integer a, Integer b, Integer c, Integer d, Integer e, Integer f, Integer g,
                          Integer h) throws Exception {
                      return "" + a + b + c + d + e + f + g + h;
                  }
              }
          )
          .test()
          .assertResult("12345678");
      }
      @Test
      public void zip9() {
          Observable.zip(Observable.just(1),
                  Observable.just(2), Observable.just(3),
                  Observable.just(4), Observable.just(5),
                  Observable.just(6), Observable.just(7),
                  Observable.just(8), Observable.just(9),
              new Function9<Integer, Integer, Integer, Integer, Integer, Integer, Integer, Integer, Integer, Object>() {
                  @Override
                  public Object apply(Integer a, Integer b, Integer c, Integer d, Integer e, Integer f, Integer g,
                          Integer h, Integer i) throws Exception {
                      return "" + a + b + c + d + e + f + g + h + i;
                  }
              }
          )
          .test()
          .assertResult("123456789");
      }
  
      @Test
      public void zip2DelayError() {
          Observable.zip(Observable.just(1).concatWith(Observable.<Integer>error(new TestException())),
                  Observable.just(2),
              new BiFunction<Integer, Integer, Object>() {
                  @Override
                  public Object apply(Integer a, Integer b) throws Exception {
                      return "" + a + b;
                  }
              }, true
          )
          .test()
          .assertFailure(TestException.class, "12");
      }
  
      @Test
      public void zip2Prefetch() {
          Observable.zip(Observable.range(1, 9),
                  Observable.range(21, 9),
              new BiFunction<Integer, Integer, Object>() {
                  @Override
                  public Object apply(Integer a, Integer b) throws Exception {
                      return "" + a + b;
                  }
              }, false, 2
          )
          .takeLast(1)
          .test()
          .assertResult("929");
      }
  
      @Test
      public void zip2DelayErrorPrefetch() {
          Observable.zip(Observable.range(1, 9).concatWith(Observable.<Integer>error(new TestException())),
                  Observable.range(21, 9),
              new BiFunction<Integer, Integer, Object>() {
                  @Override
                  public Object apply(Integer a, Integer b) throws Exception {
                      return "" + a + b;
                  }
              }, true, 2
          )
          .skip(8)
          .test()
          .assertFailure(TestException.class, "929");
      }
  
      @SuppressWarnings("unchecked")
      @Test
      public void zipArrayEmpty() {
          assertSame(Observable.empty(), Observable.zipArray(Functions.<Object[]>identity(), false, 16));
      }
  
      @Test
      public void zipArrayMany() {
          @SuppressWarnings("unchecked")
          Observable<Integer>[] arr = new Observable[10];
  
          Arrays.fill(arr, Observable.just(1));
  
          Observable.zip(Arrays.asList(arr), new Function<Object[], Object>() {
              @Override
              public Object apply(Object[] a) throws Exception {
                  return Arrays.toString(a);
              }
          })
          .test()
          .assertResult("[1, 1, 1, 1, 1, 1, 1, 1, 1, 1]");
      }
  
      @Test
      public void dispose() {
          TestHelper.checkDisposed(Observable.zip(Observable.just(1), Observable.just(1), new BiFunction<Integer, Integer, Object>() {
              @Override
              public Object apply(Integer a, Integer b) throws Exception {
                  return a + b;
              }
          }));
      }
  
      @Test
      public void noCrossBoundaryFusion() {
          for (int i = 0; i < 500; i++) {
              TestObserver<List<Object>> ts = Observable.zip(
                      Observable.just(1).observeOn(Schedulers.single()).map(new Function<Integer, Object>() {
                          @Override
                          public Object apply(Integer v) throws Exception {
                              return Thread.currentThread().getName().substring(0, 4);
                          }
                      }),
                      Observable.just(1).observeOn(Schedulers.computation()).map(new Function<Integer, Object>() {
                          @Override
                          public Object apply(Integer v) throws Exception {
                              return Thread.currentThread().getName().substring(0, 4);
                          }
                      }),
                      new BiFunction<Object, Object, List<Object>>() {
                          @Override
                          public List<Object> apply(Object t1, Object t2) throws Exception {
                              return Arrays.asList(t1, t2);
                          }
                      }
              )
              .test()
              .awaitDone(5, TimeUnit.SECONDS)
              .assertValueCount(1);
  
              List<Object> list = ts.values().get(0);
  
              assertTrue(list.toString(), list.contains("RxSi"));
              assertTrue(list.toString(), list.contains("RxCo"));
          }
      }
  
      @Test
      public void eagerDispose() {
          final PublishSubject<Integer> ps1 = PublishSubject.create();
          final PublishSubject<Integer> ps2 = PublishSubject.create();
  
          TestObserver<Integer> ts = new TestObserver<Integer>() {
              @Override
              public void onNext(Integer t) {
                  super.onNext(t);
                  cancel();
                  if (ps1.hasObservers()) {
                      onError(new IllegalStateException("ps1 not disposed"));
                  } else
                  if (ps2.hasObservers()) {
                      onError(new IllegalStateException("ps2 not disposed"));
                  } else {
                      onComplete();
                  }
              }
          };
  
          Observable.zip(ps1, ps2, new BiFunction<Integer, Integer, Integer>() {
              @Override
              public Integer apply(Integer t1, Integer t2) throws Exception {
                  return t1 + t2;
              }
          })
          .subscribe(ts);
  
          ps1.onNext(1);
          ps2.onNext(2);
          ts.assertResult(3);
      }
  }
  